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Large Waist Size May Increase Breast Cancer Risk (dateline February 21, 2000)

A new study published in the January 2000 issue of the American Journal of Epidemiology suggests that women who have excess fat around their waists may be more likely to develop breast cancer than lean women. The risk is even higher for post-menopausal women, the researchers say, because the risk of breast cancer   increases with age. Researchers followed 47,000 women from 1986 to 1994 and found that women with abdominal regions measuring more than 36 inches increased their chances of getting breast cancer by 34% compared with women who had waists measuring less than 28 inches. Though previous studies have also shown that overweight (obese) women are more likely to develop breast cancer, the link between weight and breast cancer remains controversial.

In the study, researchers found the risk of breast cancer increased more for large waisted women once they reached menopause. According to researchers, a large waist size increased breast cancer risk independently of other factors, such as age, family history of breast cancer, age at the onset of menopause, or genetics. In the study, women with some excess fat around the hip and thigh area did not appear to be at any significantly higher risk of developing breast cancer. However, previous studies have shown that women who gain a large amount of weight during adulthood do increase their chances of developing breast cancer.

In addition to a higher risk of breast cancer, obesity has also been linked to several other diseases, including heart disease , stroke, diabetes, osteoarthritis, and other types of cancer. Though women cannot control where excess fat will be deposited when they gain weight, Eugenia E. Calle, PhD, Director of Analytic Epidemiology for the American Cancer Society, said that women should try to maintain a healthy body weight throughout their lifetime and avoid gaining weight to reduce their risk of several health problems.

Other factors that may increase a woman’s risk of developing breast cancer include:

  • Age
  • Family and personal medical history
  • Genetics
  • Early onset of menstruation (before age 12). The average age of menarche (first menstruation) is 13.
  • Delayed menopause (after age 55). The average age a woman reaches menopause is 51.
  • Delayed childbirth (after age 30)
  • High-fat diet
  • Alcohol and smoking
  • Previous breast biopsy showing benign conditions such as atypical hyperplasia (a dangerous increase in the number of breast cells) or lobular carcinoma in situ
  • Early exposure to radiation therapy

To detect breast cancer at an early stage when it is most curable, all women over the age of 20 should perform breast self-examinations every month and have physician performed clinical breast exams at least every three years. Women over 40 years of age should also have annual screening mammograms in addition to annual clinical breast exams. Women at high risk of breast cancer (such as those with BRCA1 or BRCA2 gene mutations) should ask their physicians about beginning mammograms at a younger age, as early as age 25.

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